Mulder found success for South Africa taking four of the visitors’ wickets in the first innings, and could have had a five-for had they reviewed an LBW decision earlier on during Day 1.
He says he’s happy to have done his part in KG Rabada’s absence.
"Conditions did suit my skillset because the ball nips and swings a bit more so I'm chuffed that I grabbed the opportunity, but when KG comes back I'm pretty sure I'll lose that new ball."
Mulder and his team had Australia on the ropes at the close of play on Friday at 187/6, but were undone by a brilliant knock from Matt Renshaw, who went on to score 190 runs – the fourth highest Test score against the Proteas in South Africa.
Australia were eventually bowled out for 390 with the hosts losing the early wicket of Ryan Rickelton in their first innings, leaving them on 27/1 and a further 363 runs behind when bad light stopped play.
Mulder explained how they plan to go about things on the third day of the match at Kingsmead in Durban.
"You're always going to have to bat well against the Australians, especially after they posted a good score. All of us want be permanent fixtures in this team so there is a lot of motivation and commitment from within the group, and if the pitch played the way it did yesterday I think we will be able to respond well with the bat."